You are driving a heavy truck down a steep and long descent. When should you shift to an appropriate low gear?

1. A The gears are insignificant for slowing down, but you must use the speed retarders intelligently.
2. B There is no need to shift to low gear. You should shift to high gear and regulate your speed with the speed retarder, to increase safety.
3. C You should shift to low gear towards the end of the descent.
4. D You should shift to low gear at the beginning of the descent.